The Diabetes Control and Complications Trial (DCCT) results were released in 1993 (NEJM September 1993). This multicenter study proved that intensive control of blood glucose dramatically reduced the risk for microangiopathy (retinopathy 76%, nephropathy 54%, neuropathy 60%). The Epidemiology of Diabetes Interventions and Complications (EDIC) is a ten year epidemiological study of the DCCT cohort. The study will focus upon the incidence of macrovascular and renal complications by studying each participant on an annual basis. This study will provide valuable information regarding the long-term course of the complications of diabetes in a carefully characterized study population. The effects of an interaction between established and putative risk factors, including diabetes treatment and level of glycemic control for microvascular, neurologic and macrovascular long-term complications will be studied. It is anticipated that the dissemination of the new information will begin well before the planned termination of follow-up and that important results will be published in a timely fashion.